1. Field of the Invention:
This invention relates to slide fasteners, more particularly to such a slide fastener which is suitable for use on rain coats, windbreakers, cushion covers and other articles that are made of a plastics material.
2. Prior Art:
There are known slide fasteners which comprise a pair of support tapes each carrying along one of their longitudinal edges a row of coupling elements, the support tape being made of a sheet of plastics material which can be attached by means of ultrasonic or high-frequency welding to a given article made of similar plastics material. Difficulties were encountered however with the way of securing the coupling elements to such thread-free plastic tape. When this was done by sewing stitches, the needle holes would often become widened and ruptured, causing the tape to tear apart under the influence of transverse tension. To overcome this difficulty, it has been proposed to reinforce the plastic tape with a strip of woven fabric such as taffeta extending over one or the other side along the longitudinal edge of the tape to which the coupling elements are secured. This prior art proposal however has a drawback in that the reciprocal movement of the slider to open or close the fastener becomes sluggish or otherwise difficult on account of dimensional changes in the plastic tape with changing ambient temperature. Performance tests further indicate that when stress, particularly transverse tension, is applied, the tape tends to get torn along its edge portion that confronts the side flanges of the slider, thus rendering the fastener inoperative under severe conditions. It was also found difficult during the assembling of fasteners with component parts, sliders in particular, to thread these sliders through the stringers because the tapes would often get warped and so deformed due to change in the environmental temperature.